<template>
  <div class="goods-image">
    <!-- 大图容器 -->
    <div class="large" v-show="show" :style="[{ backgroundImage: `url(${images[currIndex]})` }, bgPosition]"></div>
    <!-- 中图容器 -->
    <div class="middle" ref="target">
      <img :src="images[currIndex]" alt="" />
      <div class="layer" v-show="show" :style="position"></div>
    </div>
    <!-- 小图容器 -->
    <ul class="small">
      <li v-for="(pic, index) in images" :key="pic.id" :class="{ active: index === currIndex }">
        <img :src="pic" @mouseenter="currIndex = index" alt="" />
      </li>
    </ul>
  </div>
</template>
<script>
import { reactive, ref, watch } from 'vue'
import { useMouseInElement } from '@vueuse/core'
export default {
  name: 'GoodsImage',
  props: {
    images: {
      type: Array,
      default: () => []
    }
  },
  setup(props) {
    const currIndex = ref(0)
    // 使用遮罩层的元素
    const target = ref(null)

    // 1.是否显示遮罩和大图
    const show = ref(false)
    // 2.遮罩的坐标(样式)
    const position = reactive({
      left: 0,
      top: 0
    })
    // 3.大图背景定位(样式)
    const bgPosition = reactive({
      backgroundPositionX: 0,
      backgroundPositionY: 0
    })
    // 4.使用 useMouseInElement 得到基于元素左上角的坐标和是否离开元素数据
    const { elementX, elementY, isOutside } = useMouseInElement(target)
    // 5.根据得到的数据设置样式数据和是否展示数据
    watch([elementX, elementY, isOutside], () => {
      // 横向的移动  遮罩层的显示
      if (elementX.value < 100) position.left = 0
      else if (elementX.value > 300) position.left = 200
      else position.left = elementX.value - 100

      // 纵向的移动  遮罩层的显示
      if (elementY.value < 100) position.top = 0
      else if (elementY.value > 300) position.top = 200
      else position.top = elementY.value - 100

      // 设置大背景的定位
      bgPosition.backgroundPositionX = -2 * position.left + 'px'
      bgPosition.backgroundPositionY = -2 * position.top + 'px'
      // 设置遮罩层的定位
      position.left = position.left + 'px'
      position.top = position.top + 'px'

      // 设置是否预览大图
      show.value = !isOutside.value
    })
    return { currIndex, show, position, bgPosition, target }
  }
}
</script>
<style scoped lang="less">
.goods-image {
  width: 480px;
  height: 400px;
  position: relative;
  display: flex;
  z-index: 500;
  .large {
    position: absolute;
    top: 0;
    left: 412px;
    width: 400px;
    height: 400px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    background-repeat: no-repeat;
    background-size: 800px 800px;
    background-color: #f8f8f8;
  }
  .middle {
    width: 400px;
    height: 400px;
    background: #f5f5f5;
    position: relative;
    cursor: move;
    .layer {
      width: 200px;
      height: 200px;
      background: rgba(0, 0, 0, 0.2);
      left: 0;
      top: 0;
      position: absolute;
    }
  }
  .small {
    width: 80px;
    li {
      width: 68px;
      height: 68px;
      margin-left: 12px;
      margin-bottom: 15px;
      cursor: pointer;
      &:hover,
      &.active {
        border: 2px solid @xtxColor;
      }
    }
  }
}
</style>
